Percutaneous coronary intervention in diabetics

Enhanced proliferation and migration of vascular smooth muscle cells in response to vascular injury under hyperglycemic conditions is controlled by beta3 integrin signaling

Atheroma formation and restenosis following percutaneous vascular intervention involve the growth and migration of vascular smooth muscle cells (SMCs) into neointimal lesions, in part due to changes in the extracellular matrix. While some clinical studies have suggested that, in comparison to non-diabetics, beta3 integrin inhibition in diabetic patients confers protection from restenosis, little is known regarding the role of beta3 integrin inhibition on SMC responses in this context. To understand the molecular mechanisms underlying integrin-mediated regulation of SMC function in diabetes, we examined SMC responses in diabetic mice deficient in integrin beta3 and observed that the integrin was required for enhanced proliferation, migration and extracellular regulated kinase (ERK) activation. Hyperglycemia-enhanced membrane recruitment and catalytic activity of PKCbeta in an integrin beta3-dependent manner. Hyperglycemia also promoted SMC filopodia formation and cell migration, both of which required alphaVbeta3, PKCbeta, and ERK activity. Furthermore, the integrin-kinase association was regulated by the alphaVbeta3 integrin ligand thrombospondin and the integrin modulator Rap1 under conditions of hyperglycemia. These results suggest that there are differences in SMC responses to vascular injury depending on the presence or absence of hyperglycemia and that SMC response under hyperglycemic conditions is largely mediated through beta3 integrin signaling.

Diabetes mellitus: a prothrombotic state implications for outcomes after coronary revascularization

Coronary stent thrombosis is a serious problem in the drug-eluting stent era. Despite aggressive antiplatelet therapy during and after percutaneous coronary intervention (PCI), the incidence of sub-acute stent thrombosis remains approximately 0.5%–2%, which may represent a catastrophic clinical situation. Both procedural factors and discontinuation of antiplatelet therapy are normally associated with this event. We report on simultaneous stent thromboses of two drug-eluting stents implanted in two different vessels, which resulted in a life-threatening clinical condition. Possible contributing factors that led to synergistic thrombotic effects are discussed.

The effect of drug-eluting stents on intermediate angiographic and clinical outcomes in diabetic patients: insights from randomized clinical trials

OBJECTIVE

Implantation of drug-eluting stents has emerged as the predominant percutaneous revascularization strategy in diabetic patients, despite limited outcomes data. Accordingly, our aim was to conduct a meta-analysis to assess the benefit and safety profile of drug-eluting stents in diabetic patients.

METHODS

We included randomized trials comparing either the paclitaxel- or sirolimus-eluting stent with a bare-metal stent or with each other in diabetic patients during a follow-up of at least 6 months.

RESULTS

A total of 16 studies were identified, which included 2951 diabetic patients who were followed up for 6 to 12 months. Target lesion revascularization was less frequently performed in patients who received drug-eluting stents compared with bare-metal stents (risk ratio [RR] 0.35, 95% CI 0.27-0.46, P < .0001). Similar reductions were noted in the incidence of major adverse cardiovascular events (RR 0.42, 95% CI 0.31-0.56, P < .0001), in-segment restenosis (RR 0.31, 95% CI 0.25-0.40, P < .0001), and non-Q-wave myocardial infarction (RR 0.57, 95% CI 0.32-0.99, P = .046). Event rates were similar for Q-wave myocardial infarction (RR 0.72, 95% CI 0.25-2.07, P = .54), death (RR 0.64, 95% CI 0.32-1.28, P = .20), and stent thrombosis (RR 0.41, 95% CI 0.13-1.27, P = .12).

CONCLUSIONS

In conclusion, diabetic patients who receive drug-eluting stents have a significantly lower incidence of target lesion revascularization, in-segment restenosis and myocardial infarction at 6 to 12 months, compared with bare-metal stents. The rates of mortality and stent thrombosis are similar.

Restenosis related to percutaneous coronary intervention has been solved?

Percutaneous coronary intervention (PCI) has become the most important revascularization method in the treatment of coronary artery disease. The major problem in PCI has been renarrowing of the dilated vessel after the procedure (restenosis). The best results in the prevention of restenosis have been obtained by covering the stent with drugs that inhibit cellular growth, thus limiting excessive scar formation inside of the stent. With drug-eluting stents, restenosis has been reduced to one-tenth compared with balloon angioplasty and to one-fourth compared to bare metal stents. Due to drug-eluting stents, PCI is an alternative to bypass surgery. However, restenosis will remain a challenge due to the increased number of procedures and more difficult disease treated with PCI.

Does diabetes mellitus abolish the beneficial effect of primary coronary angioplasty on long-term risk of reinfarction after acute ST-segment elevation myocardial infarction compared with fibrinolysis? (A DANAMI-2 substudy)

Little is known about the effect of diabetes mellitus on long-term clinical outcome after primary percutaneous coronary intervention (pPCI) compared with fibrinolysis in patients who have acute ST-elevation myocardial infarction. We analyzed 3-year clinical outcome in diabetic patients and nondiabetic patients who had been randomized to fibrinolysis or pPCI in the DANAMI-2 trial to compare long-term clinical outcome. The primary end point was a composite of death, clinical reinfarction, or disabling stroke. Median follow-up was 3.8 years. Among 1,572 consecutive patients who had ST-elevation myocardial infarction and were randomized to pPCI or fibrinolysis, 173 (11.0%) had diabetes mellitus; 60 of these patients received metformin treatment and were excluded. After 3 years no difference was found between diabetic patients who underwent pPCI versus fibrinolysis (combined event p=0.37, reinfarction p=0.06 in favor of fibrinolysis), whereas pPCI was superior to fibrinolysis in nondiabetic patients (combined event p=0.002, clinical reinfarction p<0.001). Three-year incidence of clinical reinfarction analyzed with Cox's regression showed that pPCI compared with fibrinolysis increased the relative risk of clinical reinfarction in diabetic patients (relative risk 2.57, 95% confidence interval 1.48 to 4.46, p <0.001) but decreased the risk in nondiabetic patients (relative risk 0.52, 95% confidence interval 0.36 to 0.74, p<0.001). In conclusion, from the DANAMI-2 trial we hypothesize that diabetes may abolish the beneficial effect of pPCI on long-term risk of clinical reinfarction.